The scarcity of spectrum channels resides in the limited bandwidth resource and the exploding demand from spectrum-based services and devices. To help ease this scarcity, the concept of cognitive radio networks (CRNs) is proposed, where licensed spectrum holders (primary users) may lease their channels to unlicensed users (secondary users). Many CRN auctions are thus designed to incentivize primary users (PUs) to share their idle channels with secondary users (SUs). Most of these auctions assume that a transmitting PU does not lease its channel to SUs; if it leases its channel to SUs, it does not transmit itself. To further utilize the resource, researchers have studied the scenario where a transmitting PU is allowed to lease its channels to SUs if the transmissions of the SUs do not undermine the transmission of the PU. However, the study assumes that there is only one PU who owns the licensed channels, whereas in practice, channels may be contributed by multiple PUs. This prevents the result of the study from being directly applied to the multi-PU scenario, as the potential competitions among the PUs are neglected. We extend the scenario to the CRN with multiple PUs and propose TDSA-PS as a Truthful Double Spectrum Auction with transmitting Primary users Sharing. We prove that TDSA-PS is truthful, individually rational, budget-balanced, and computationally efficient.